An OCI medical device includes a coherent light source, a light sensor, a first processing unit adapted to calculate OCI Data from the light sensor, a control unit which allows taking or loading of at least one Reference OCI Value, a second processing unit adapted to calculate the Intra-Individual Relative Assessment of the OCI Data of an Imaging Zone and the at least one OCI Reference Value, and display means adapted to show at least one Relative OCI Value. Uses and a method for assessing the blood flow of a body region use OCI imaging and include an Intra-Individual Relative Assessment between OCI Data of the Imaging Zone and at least one Reference OCI Value.